WO96/29195 discloses a square baler which, instead of using the compacting plunger to unload tied bales from the bale case, comprises an auxiliary ejector system to enable the operator to off-load completed bales. The ejector system comprises a shuttle assembly housed within hollow rails of the bale case. The shuttle assembly consists of a frame that is reciprocated in the direction of movement of the compacting plunger and has dogs projecting upwards from it to engage in the underside of the bales. The dogs grip the bale only during the forward stroke of the shuttle assembly, that is to say when it is moving towards the discharge outlet of the bale case, and slip relative to the underside of the bale during the return stroke. In this way, the reciprocation of the shuttle assembly incrementally advances the bales towards the discharge outlet.
The ejector mechanism of WO96/29195 is controllable to enable the operator to select whether to discharge only the last bale in the bale case (the one nearest the discharge outlet) or both the last bale and the one before it. To achieve this, the dogs are arranged on the shuttle in a longitudinally extending series and at least some of the dogs are controllable by the operator using a selector assembly so that the controlled dogs may be positioned either to extend into the bale case or to be retracted from it.
Apart from the complexity resulting from the need to control dogs individually, the ejector system of WO96/29195 suffers from the disadvantage that the operator needs first to inspect the position of the bales in the bale case in order to decide on which of the dogs to activate.
To avoid these disadvantages, the Applicants' earlier patent application number EP 08154199.7 discloses a square baler having a bale case within which crop is compacted by means of a plunger, a discharge outlet at one end of the bale case and an ejector system for advancing bales towards the discharge outlet independently of the movement of the compacting plunger. The ejector system comprises a shuttle assembly mounted in a wall of the bale case for reciprocation parallel to the direction of movement of the bales in the bale case, and at least one dog mounted on the shuttle assembly to engage in the last bale in the bale case positioned nearest the discharge outlet and to advance the bale incrementally out of the discharge outlet in response to reciprocation of the shuttle assembly. A second shuttle assembly is mounted in a wall of the bale case for reciprocation independently of the first shuttle assembly, the second shuttle assembly having at least one dog mounted thereon to engage in the next-to-last bale in the bale case.
In one embodiment, the second shuttle assembly has a series of dogs staggered over its entire length and is capable of advancing bales as far as the discharge outlet of the bale case. In this case, reciprocation of the second shuttle assembly on its own will suffice to advance both the last bale and the next-to-last bale to the discharge outlet.
In an alternative embodiment, the second shuttle assembly is designed to move the next-to-last bale only as far as a position where it will be taken up by the first shuttle assembly. In this case, both shuttles need to be reciprocated to discharge the next-to-last bale in the bale case.
Without regard to the exact positions of the completed bales in the bale case, the operator may thus elect to discharge only the last bale by operating the first of the shuttle assemblies or to discharge both the last and next-to-last bale by reciprocating the second shuttle assembly either on its own or in conjunction with the first shuttle assembly.
An important advantage of EP 08154199.7 is that the dogs do not need to be controlled, i.e. selectively enabled and disabled. Each dog is instead pivotably mounted on the shuttle assembly and designed to act in a manner analogous to the pawl of a pawl and ratchet. Thus, each dog will pivot into an extended gripping position during the forward movements of the shuttle to advance the bale towards the discharge outlet and will retract during reverse movements of the shuttle assembly to slip relative to the bale.
When using pivotable dogs, they may be biased into their extended position by gravity or by means of a spring. EP 08154199.7 also teaches that the dogs may be designed to protrude slightly into the bale case when retracted so that they will be raised automatically into their extended position as they grip into a bale.
The present invention seeks to improve on the design of the dogs used in the reciprocating ejector assemblies such as for example known from EP 08154199.7.
Each dog in EP 08154199.7 comprises a generally triangular plate that is pivoted in such a manner that its own weight rotates it into a retracted rest position in which its side lies nearly level with the floor of the bale case. The small part of the dog that projects above the floor digs into the bale when the shuttle assembly is moved towards the discharge outlet of the baler and the resistance that it encounters rotates the dog into its raised position. The bale is now gripped and moves with the shuttle assembly. During the movement of the shuttle away in the opposite direction, the dog returns to the rest position in which it is retracted and no long grips the bale. Two stops are provided against which the dog rests in its retracted and extended position, respectively.